Q. My teenage daughter just found out she has a sun allergy. Can you explain what her symptoms mean, and what type of sunscreen she should be using to best protect herself?

Dr. Skotnicki:Many patients develop itchy, red, raised lesions while on a sun holiday, or during the spring in North America. Though this reaction is often referred to as a sun allergy, it’s not a true allergic reaction. The correct medical term for this sensitivity is Polymorphous Light Eruption[1], and it’s characterized medically as an abnormal skin reaction to ultraviolet light.

Lesions usually occur on the second or third day of prolonged sun exposure, with reactions lasting about seven days. The condition improves after repeated sun exposure as the skin “hardens” and the abnormal reaction to the sun decreases – which is why it occurs during the spring in Canada and the northern U.S. and improves over the summer months.

The best treatment is prevention. Happily, the newer sunscreen technology is enough to block most reactions. I recommend Ombrelle SPF 45 for kids as it contains titanium dioxide, stabilized Parsol 1789 and Mexoryl SX – all ingredients that block the longer UVA wavelengths, thought to be the primary cause of Polymorphous Light Eruption. I also like La Roche-Posay Anthélios Lait SPF 45, which is fragrance-and preservative-free, and the Anthélios L SPF 60 sunscreen, for heavy-duty protection.

Remember to apply sunscreen 30 minutes before sun exposure and reapply every two hours.